ios - 如何使用 Swift 解析 PDF 页面中的内容

Question

文档对我来说不是很清楚。到目前为止，我认为我需要设置一个 CGPDFOperatorTable，然后为每个 PDF 页面创建一个 CGPDFContentStreamCreateWithPage 和 CGPDFScannerCreate。

文档提到了设置回调，但我不清楚如何设置。如何从页面中实际获取内容？

到目前为止，这是我的代码。

    let pdfURL = NSBundle.mainBundle().URLForResource("titleofdocument", withExtension: "pdf")

    // Create pdf document
    let pdfDoc = CGPDFDocumentCreateWithURL(pdfURL)

    // Nr of pages in this PF
    let numberOfPages = CGPDFDocumentGetNumberOfPages(pdfDoc) as Int

    if numberOfPages <= 0 {
        // The number of pages is zero
        return
    }

    let myTable = CGPDFOperatorTableCreate()

    // lets go through every page
    for pageNr in 1...numberOfPages {

        let thisPage = CGPDFDocumentGetPage(pdfDoc, pageNr)
        let myContentStream = CGPDFContentStreamCreateWithPage(thisPage)
        let myScanner = CGPDFScannerCreate(myContentStream, myTable, nil)

        CGPDFScannerScan(myScanner)

        // Search for Content here?
        // ??

        CGPDFScannerRelease(myScanner)
        CGPDFContentStreamRelease(myContentStream)

    }

    // Release Table
    CGPDFOperatorTableRelease(myTable)

这是一个类似的问题:PDF Parsing with SWIFT但还没有答案。

Answer 1

这是一个在 Swift 中实现的回调示例:

    let operatorTableRef = CGPDFOperatorTableCreate()

    CGPDFOperatorTableSetCallback(operatorTableRef, "BT") { (scanner, info) in
        print("Begin text object")
    }
    CGPDFOperatorTableSetCallback(operatorTableRef, "ET") { (scanner, info) in
        print("End text object")
    }
    CGPDFOperatorTableSetCallback(operatorTableRef, "Tf") { (scanner, info) in
        print("Select font")
    }
    CGPDFOperatorTableSetCallback(operatorTableRef, "Tj") { (scanner, info) in
        print("Show text")
    }
    CGPDFOperatorTableSetCallback(operatorTableRef, "TJ") { (scanner, info) in
        print("Show text, allowing individual glyph positioning")
    }

    let numPages = CGPDFDocumentGetNumberOfPages(pdfDocument)
    for pageNum in 1...numPages {
        let page = CGPDFDocumentGetPage(pdfDocument, pageNum)
        let stream = CGPDFContentStreamCreateWithPage(page)
        let scanner = CGPDFScannerCreate(stream, operatorTableRef, nil)
        CGPDFScannerScan(scanner)
        CGPDFScannerRelease(scanner)
        CGPDFContentStreamRelease(stream)
    }